Twist1 knockdown leads to pronounced signs of chronic inflammation in murine arthritis. Representative hematoxylin/eosin staining of knee joint sections (d 21) showing hyperplasia of the lining cells and the subintimal layer with pannus formation (bar, 200 μm), more pronounced infiltration of CD3⁺ T cells (magnification of boxed areas in top row; bar, 100 μm) and stronger expression of TNF-α (red) especially of the enlarged lining and sublining layer (magnification of boxed areas in second row; bar, 50 μm) after transfer of Th1 cells expressing a twist1-targeting shRNA as compared with the control group. Data are representative of five mice each.